What is the appropriate oseltamivir (Tamiflu) dose for a 23‑lb (≈10‑kg) child who is at least two weeks old with normal renal function?

Oseltamivir Dosing for a 23‑lb Child

For a 23‑lb (10.4‑kg) child who is at least 2 weeks old with normal renal function, the recommended oseltamivir dose is 30 mg orally twice daily for 5 days (treatment) or 30 mg once daily for 10 days (prophylaxis). 1

Weight‑Based Dosing Algorithm

A 23‑lb child falls into the ≤15 kg (≤33 lb) weight bracket, which determines the dose for children ≥12 months of age. 1, 2

Treatment Regimen (Acute Influenza)

• Dose & Schedule: 30 mg orally twice daily for 5 days 1, 2
• Formulation: Using the 6 mg/mL oral suspension, each 30 mg dose equals 5 mL 1, 2
• Capsule Option: One 30 mg capsule may be used if the child can swallow it; capsules can be opened and mixed with sweetened liquid if needed 1

Prophylaxis Regimen (Post‑Exposure)

• Dose & Schedule: 30 mg orally once daily for 10 days after close contact with an infected individual 1, 2
• Volume: 5 mL of the 6 mg/mL suspension once daily 1

Age‑Specific Considerations

If the child is younger than 12 months, the dosing changes to a mg/kg‑based calculation rather than the categorical weight‑based approach. 1, 2

For Infants 9–11 Months

• Treatment: 3.5 mg/kg per dose twice daily for 5 days 1, 2
• For a 10.4 kg infant: 36.4 mg per dose (≈6 mL of 6 mg/mL suspension) 2

For Term Infants 0–8 Months

• Treatment: 3.0 mg/kg per dose twice daily for 5 days 1, 2
• For a 10.4 kg infant: 31.2 mg per dose (≈5.2 mL of 6 mg/mL suspension) 2

For Preterm Infants

• Dosing is based on post‑menstrual age (PMA) = gestational age + chronological age 1, 2
• <38 weeks PMA: 1.0 mg/kg twice daily 1, 2
• 38–40 weeks PMA: 1.5 mg/kg twice daily 1, 2
• >40 weeks PMA: 3.0 mg/kg twice daily 1, 2

Administration Guidance

• Take with food to significantly reduce nausea and vomiting, which occur in approximately 10–15% of patients 1, 3
• Use a calibrated oral syringe (3 mL or 5 mL) for accurate measurement; household spoons should not be used 1, 2
• If commercial suspension is unavailable, a pharmacy can compound a 6 mg/mL suspension according to package‑insert instructions 1

Timing Considerations

• Treatment should be initiated within 48 hours of symptom onset for maximum effectiveness; earlier initiation (within 12–24 hours) yields the greatest benefit 1, 3
• Prophylaxis should be started within 48 hours following close contact with an infected individual 1

Common Pitfalls to Avoid

• Do not round up to 45 mg for a 23‑lb child; this dose is reserved for children >15 kg to ≤23 kg (>33 to 51 lb) 1, 2
• Do not use the 30 mg categorical dose for infants <12 months; they require mg/kg‑based dosing 1, 2
• Do not apply term‑infant dosing to preterm infants without calculating PMA; using term doses can cause toxic accumulation 1, 2
• Do not confuse treatment dosing (twice daily) with prophylaxis dosing (once daily) 1
• Do not delay treatment while awaiting laboratory confirmation in high‑risk patients 4

Renal Function Adjustments

• Normal renal function: No dose modification required 1
• Creatinine clearance 10–30 mL/min: Reduce treatment dose to 30 mg once daily (instead of twice daily) for 5 days; prophylaxis dose is 30 mg once daily or 75 mg every other day for 10 days 1, 2

Safety Profile

• The most common adverse effects are gastrointestinal (nausea, vomiting, diarrhea), occurring in 10–15% of patients and typically resolving within 1–2 days 1, 3
• Only approximately 1% of patients discontinue oseltamivir due to gastrointestinal side effects 1
• When age‑appropriate dosing is applied, the safety profile in children is comparable to that in adults 1, 5